linux/drivers/misc/lkdtm/core.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Linux Kernel Dump Test Module for testing kernel crashes conditions:
   4 * induces system failures at predefined crashpoints and under predefined
   5 * operational conditions in order to evaluate the reliability of kernel
   6 * sanity checking and crash dumps obtained using different dumping
   7 * solutions.
   8 *
   9 * Copyright (C) IBM Corporation, 2006
  10 *
  11 * Author: Ankita Garg <ankita@in.ibm.com>
  12 *
  13 * It is adapted from the Linux Kernel Dump Test Tool by
  14 * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
  15 *
  16 * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
  17 *
  18 * See Documentation/fault-injection/provoke-crashes.rst for instructions
  19 */
  20#include "lkdtm.h"
  21#include <linux/fs.h>
  22#include <linux/module.h>
  23#include <linux/buffer_head.h>
  24#include <linux/kprobes.h>
  25#include <linux/list.h>
  26#include <linux/init.h>
  27#include <linux/slab.h>
  28#include <linux/debugfs.h>
  29#include <linux/init.h>
  30
  31#define DEFAULT_COUNT 10
  32
  33static int lkdtm_debugfs_open(struct inode *inode, struct file *file);
  34static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
  35                size_t count, loff_t *off);
  36static ssize_t direct_entry(struct file *f, const char __user *user_buf,
  37                            size_t count, loff_t *off);
  38
  39#ifdef CONFIG_KPROBES
  40static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
  41static ssize_t lkdtm_debugfs_entry(struct file *f,
  42                                   const char __user *user_buf,
  43                                   size_t count, loff_t *off);
  44# define CRASHPOINT_KPROBE(_symbol)                             \
  45                .kprobe = {                                     \
  46                        .symbol_name = (_symbol),               \
  47                        .pre_handler = lkdtm_kprobe_handler,    \
  48                },
  49# define CRASHPOINT_WRITE(_symbol)                              \
  50                (_symbol) ? lkdtm_debugfs_entry : direct_entry
  51#else
  52# define CRASHPOINT_KPROBE(_symbol)
  53# define CRASHPOINT_WRITE(_symbol)              direct_entry
  54#endif
  55
  56/* Crash points */
  57struct crashpoint {
  58        const char *name;
  59        const struct file_operations fops;
  60        struct kprobe kprobe;
  61};
  62
  63#define CRASHPOINT(_name, _symbol)                              \
  64        {                                                       \
  65                .name = _name,                                  \
  66                .fops = {                                       \
  67                        .read   = lkdtm_debugfs_read,           \
  68                        .llseek = generic_file_llseek,          \
  69                        .open   = lkdtm_debugfs_open,           \
  70                        .write  = CRASHPOINT_WRITE(_symbol)     \
  71                },                                              \
  72                CRASHPOINT_KPROBE(_symbol)                      \
  73        }
  74
  75/* Define the possible places where we can trigger a crash point. */
  76static struct crashpoint crashpoints[] = {
  77        CRASHPOINT("DIRECT",             NULL),
  78#ifdef CONFIG_KPROBES
  79        CRASHPOINT("INT_HARDWARE_ENTRY", "do_IRQ"),
  80        CRASHPOINT("INT_HW_IRQ_EN",      "handle_irq_event"),
  81        CRASHPOINT("INT_TASKLET_ENTRY",  "tasklet_action"),
  82        CRASHPOINT("FS_DEVRW",           "ll_rw_block"),
  83        CRASHPOINT("MEM_SWAPOUT",        "shrink_inactive_list"),
  84        CRASHPOINT("TIMERADD",           "hrtimer_start"),
  85        CRASHPOINT("SCSI_QUEUE_RQ",      "scsi_queue_rq"),
  86        CRASHPOINT("IDE_CORE_CP",        "generic_ide_ioctl"),
  87#endif
  88};
  89
  90
  91/* Crash types. */
  92struct crashtype {
  93        const char *name;
  94        void (*func)(void);
  95};
  96
  97#define CRASHTYPE(_name)                        \
  98        {                                       \
  99                .name = __stringify(_name),     \
 100                .func = lkdtm_ ## _name,        \
 101        }
 102
 103/* Define the possible types of crashes that can be triggered. */
 104static const struct crashtype crashtypes[] = {
 105        CRASHTYPE(PANIC),
 106        CRASHTYPE(BUG),
 107        CRASHTYPE(WARNING),
 108        CRASHTYPE(WARNING_MESSAGE),
 109        CRASHTYPE(EXCEPTION),
 110        CRASHTYPE(LOOP),
 111        CRASHTYPE(EXHAUST_STACK),
 112        CRASHTYPE(CORRUPT_STACK),
 113        CRASHTYPE(CORRUPT_STACK_STRONG),
 114        CRASHTYPE(REPORT_STACK),
 115        CRASHTYPE(CORRUPT_LIST_ADD),
 116        CRASHTYPE(CORRUPT_LIST_DEL),
 117        CRASHTYPE(STACK_GUARD_PAGE_LEADING),
 118        CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
 119        CRASHTYPE(UNSET_SMEP),
 120        CRASHTYPE(CORRUPT_PAC),
 121        CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
 122        CRASHTYPE(FORTIFY_OBJECT),
 123        CRASHTYPE(FORTIFY_SUBOBJECT),
 124        CRASHTYPE(SLAB_LINEAR_OVERFLOW),
 125        CRASHTYPE(VMALLOC_LINEAR_OVERFLOW),
 126        CRASHTYPE(WRITE_AFTER_FREE),
 127        CRASHTYPE(READ_AFTER_FREE),
 128        CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
 129        CRASHTYPE(READ_BUDDY_AFTER_FREE),
 130        CRASHTYPE(SLAB_INIT_ON_ALLOC),
 131        CRASHTYPE(BUDDY_INIT_ON_ALLOC),
 132        CRASHTYPE(SLAB_FREE_DOUBLE),
 133        CRASHTYPE(SLAB_FREE_CROSS),
 134        CRASHTYPE(SLAB_FREE_PAGE),
 135        CRASHTYPE(SOFTLOCKUP),
 136        CRASHTYPE(HARDLOCKUP),
 137        CRASHTYPE(SPINLOCKUP),
 138        CRASHTYPE(HUNG_TASK),
 139        CRASHTYPE(OVERFLOW_SIGNED),
 140        CRASHTYPE(OVERFLOW_UNSIGNED),
 141        CRASHTYPE(ARRAY_BOUNDS),
 142        CRASHTYPE(EXEC_DATA),
 143        CRASHTYPE(EXEC_STACK),
 144        CRASHTYPE(EXEC_KMALLOC),
 145        CRASHTYPE(EXEC_VMALLOC),
 146        CRASHTYPE(EXEC_RODATA),
 147        CRASHTYPE(EXEC_USERSPACE),
 148        CRASHTYPE(EXEC_NULL),
 149        CRASHTYPE(ACCESS_USERSPACE),
 150        CRASHTYPE(ACCESS_NULL),
 151        CRASHTYPE(WRITE_RO),
 152        CRASHTYPE(WRITE_RO_AFTER_INIT),
 153        CRASHTYPE(WRITE_KERN),
 154        CRASHTYPE(REFCOUNT_INC_OVERFLOW),
 155        CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
 156        CRASHTYPE(REFCOUNT_INC_NOT_ZERO_OVERFLOW),
 157        CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_OVERFLOW),
 158        CRASHTYPE(REFCOUNT_DEC_ZERO),
 159        CRASHTYPE(REFCOUNT_DEC_NEGATIVE),
 160        CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE),
 161        CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE),
 162        CRASHTYPE(REFCOUNT_INC_ZERO),
 163        CRASHTYPE(REFCOUNT_ADD_ZERO),
 164        CRASHTYPE(REFCOUNT_INC_SATURATED),
 165        CRASHTYPE(REFCOUNT_DEC_SATURATED),
 166        CRASHTYPE(REFCOUNT_ADD_SATURATED),
 167        CRASHTYPE(REFCOUNT_INC_NOT_ZERO_SATURATED),
 168        CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED),
 169        CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED),
 170        CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED),
 171        CRASHTYPE(REFCOUNT_TIMING),
 172        CRASHTYPE(ATOMIC_TIMING),
 173        CRASHTYPE(USERCOPY_HEAP_SIZE_TO),
 174        CRASHTYPE(USERCOPY_HEAP_SIZE_FROM),
 175        CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO),
 176        CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM),
 177        CRASHTYPE(USERCOPY_STACK_FRAME_TO),
 178        CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
 179        CRASHTYPE(USERCOPY_STACK_BEYOND),
 180        CRASHTYPE(USERCOPY_KERNEL),
 181        CRASHTYPE(STACKLEAK_ERASING),
 182        CRASHTYPE(CFI_FORWARD_PROTO),
 183        CRASHTYPE(FORTIFIED_STRSCPY),
 184        CRASHTYPE(DOUBLE_FAULT),
 185#ifdef CONFIG_PPC_BOOK3S_64
 186        CRASHTYPE(PPC_SLB_MULTIHIT),
 187#endif
 188};
 189
 190
 191/* Global kprobe entry and crashtype. */
 192static struct kprobe *lkdtm_kprobe;
 193static struct crashpoint *lkdtm_crashpoint;
 194static const struct crashtype *lkdtm_crashtype;
 195
 196/* Module parameters */
 197static int recur_count = -1;
 198module_param(recur_count, int, 0644);
 199MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 200
 201static char* cpoint_name;
 202module_param(cpoint_name, charp, 0444);
 203MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 204
 205static char* cpoint_type;
 206module_param(cpoint_type, charp, 0444);
 207MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 208                                "hitting the crash point");
 209
 210static int cpoint_count = DEFAULT_COUNT;
 211module_param(cpoint_count, int, 0644);
 212MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 213                                "crash point is to be hit to trigger action");
 214
 215
 216/* Return the crashtype number or NULL if the name is invalid */
 217static const struct crashtype *find_crashtype(const char *name)
 218{
 219        int i;
 220
 221        for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 222                if (!strcmp(name, crashtypes[i].name))
 223                        return &crashtypes[i];
 224        }
 225
 226        return NULL;
 227}
 228
 229/*
 230 * This is forced noinline just so it distinctly shows up in the stackdump
 231 * which makes validation of expected lkdtm crashes easier.
 232 */
 233static noinline void lkdtm_do_action(const struct crashtype *crashtype)
 234{
 235        if (WARN_ON(!crashtype || !crashtype->func))
 236                return;
 237        crashtype->func();
 238}
 239
 240static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 241                                 const struct crashtype *crashtype)
 242{
 243        int ret;
 244
 245        /* If this doesn't have a symbol, just call immediately. */
 246        if (!crashpoint->kprobe.symbol_name) {
 247                lkdtm_do_action(crashtype);
 248                return 0;
 249        }
 250
 251        if (lkdtm_kprobe != NULL)
 252                unregister_kprobe(lkdtm_kprobe);
 253
 254        lkdtm_crashpoint = crashpoint;
 255        lkdtm_crashtype = crashtype;
 256        lkdtm_kprobe = &crashpoint->kprobe;
 257        ret = register_kprobe(lkdtm_kprobe);
 258        if (ret < 0) {
 259                pr_info("Couldn't register kprobe %s\n",
 260                        crashpoint->kprobe.symbol_name);
 261                lkdtm_kprobe = NULL;
 262                lkdtm_crashpoint = NULL;
 263                lkdtm_crashtype = NULL;
 264        }
 265
 266        return ret;
 267}
 268
 269#ifdef CONFIG_KPROBES
 270/* Global crash counter and spinlock. */
 271static int crash_count = DEFAULT_COUNT;
 272static DEFINE_SPINLOCK(crash_count_lock);
 273
 274/* Called by kprobe entry points. */
 275static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 276{
 277        unsigned long flags;
 278        bool do_it = false;
 279
 280        if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 281                return 0;
 282
 283        spin_lock_irqsave(&crash_count_lock, flags);
 284        crash_count--;
 285        pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 286                lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 287
 288        if (crash_count == 0) {
 289                do_it = true;
 290                crash_count = cpoint_count;
 291        }
 292        spin_unlock_irqrestore(&crash_count_lock, flags);
 293
 294        if (do_it)
 295                lkdtm_do_action(lkdtm_crashtype);
 296
 297        return 0;
 298}
 299
 300static ssize_t lkdtm_debugfs_entry(struct file *f,
 301                                   const char __user *user_buf,
 302                                   size_t count, loff_t *off)
 303{
 304        struct crashpoint *crashpoint = file_inode(f)->i_private;
 305        const struct crashtype *crashtype = NULL;
 306        char *buf;
 307        int err;
 308
 309        if (count >= PAGE_SIZE)
 310                return -EINVAL;
 311
 312        buf = (char *)__get_free_page(GFP_KERNEL);
 313        if (!buf)
 314                return -ENOMEM;
 315        if (copy_from_user(buf, user_buf, count)) {
 316                free_page((unsigned long) buf);
 317                return -EFAULT;
 318        }
 319        /* NULL-terminate and remove enter */
 320        buf[count] = '\0';
 321        strim(buf);
 322
 323        crashtype = find_crashtype(buf);
 324        free_page((unsigned long)buf);
 325
 326        if (!crashtype)
 327                return -EINVAL;
 328
 329        err = lkdtm_register_cpoint(crashpoint, crashtype);
 330        if (err < 0)
 331                return err;
 332
 333        *off += count;
 334
 335        return count;
 336}
 337#endif
 338
 339/* Generic read callback that just prints out the available crash types */
 340static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 341                size_t count, loff_t *off)
 342{
 343        char *buf;
 344        int i, n, out;
 345
 346        buf = (char *)__get_free_page(GFP_KERNEL);
 347        if (buf == NULL)
 348                return -ENOMEM;
 349
 350        n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 351        for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 352                n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 353                              crashtypes[i].name);
 354        }
 355        buf[n] = '\0';
 356
 357        out = simple_read_from_buffer(user_buf, count, off,
 358                                      buf, n);
 359        free_page((unsigned long) buf);
 360
 361        return out;
 362}
 363
 364static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 365{
 366        return 0;
 367}
 368
 369/* Special entry to just crash directly. Available without KPROBEs */
 370static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 371                size_t count, loff_t *off)
 372{
 373        const struct crashtype *crashtype;
 374        char *buf;
 375
 376        if (count >= PAGE_SIZE)
 377                return -EINVAL;
 378        if (count < 1)
 379                return -EINVAL;
 380
 381        buf = (char *)__get_free_page(GFP_KERNEL);
 382        if (!buf)
 383                return -ENOMEM;
 384        if (copy_from_user(buf, user_buf, count)) {
 385                free_page((unsigned long) buf);
 386                return -EFAULT;
 387        }
 388        /* NULL-terminate and remove enter */
 389        buf[count] = '\0';
 390        strim(buf);
 391
 392        crashtype = find_crashtype(buf);
 393        free_page((unsigned long) buf);
 394        if (!crashtype)
 395                return -EINVAL;
 396
 397        pr_info("Performing direct entry %s\n", crashtype->name);
 398        lkdtm_do_action(crashtype);
 399        *off += count;
 400
 401        return count;
 402}
 403
 404#ifndef MODULE
 405/*
 406 * To avoid needing to export parse_args(), just don't use this code
 407 * when LKDTM is built as a module.
 408 */
 409struct check_cmdline_args {
 410        const char *param;
 411        int value;
 412};
 413
 414static int lkdtm_parse_one(char *param, char *val,
 415                           const char *unused, void *arg)
 416{
 417        struct check_cmdline_args *args = arg;
 418
 419        /* short circuit if we already found a value. */
 420        if (args->value != -ESRCH)
 421                return 0;
 422        if (strncmp(param, args->param, strlen(args->param)) == 0) {
 423                bool bool_result;
 424                int ret;
 425
 426                ret = kstrtobool(val, &bool_result);
 427                if (ret == 0)
 428                        args->value = bool_result;
 429        }
 430        return 0;
 431}
 432
 433int lkdtm_check_bool_cmdline(const char *param)
 434{
 435        char *command_line;
 436        struct check_cmdline_args args = {
 437                .param = param,
 438                .value = -ESRCH,
 439        };
 440
 441        command_line = kstrdup(saved_command_line, GFP_KERNEL);
 442        if (!command_line)
 443                return -ENOMEM;
 444
 445        parse_args("Setting sysctl args", command_line,
 446                   NULL, 0, -1, -1, &args, lkdtm_parse_one);
 447
 448        kfree(command_line);
 449
 450        return args.value;
 451}
 452#endif
 453
 454static struct dentry *lkdtm_debugfs_root;
 455
 456static int __init lkdtm_module_init(void)
 457{
 458        struct crashpoint *crashpoint = NULL;
 459        const struct crashtype *crashtype = NULL;
 460        int ret;
 461        int i;
 462
 463        /* Neither or both of these need to be set */
 464        if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 465                pr_err("Need both cpoint_type and cpoint_name or neither\n");
 466                return -EINVAL;
 467        }
 468
 469        if (cpoint_type) {
 470                crashtype = find_crashtype(cpoint_type);
 471                if (!crashtype) {
 472                        pr_err("Unknown crashtype '%s'\n", cpoint_type);
 473                        return -EINVAL;
 474                }
 475        }
 476
 477        if (cpoint_name) {
 478                for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 479                        if (!strcmp(cpoint_name, crashpoints[i].name))
 480                                crashpoint = &crashpoints[i];
 481                }
 482
 483                /* Refuse unknown crashpoints. */
 484                if (!crashpoint) {
 485                        pr_err("Invalid crashpoint %s\n", cpoint_name);
 486                        return -EINVAL;
 487                }
 488        }
 489
 490#ifdef CONFIG_KPROBES
 491        /* Set crash count. */
 492        crash_count = cpoint_count;
 493#endif
 494
 495        /* Handle test-specific initialization. */
 496        lkdtm_bugs_init(&recur_count);
 497        lkdtm_perms_init();
 498        lkdtm_usercopy_init();
 499        lkdtm_heap_init();
 500
 501        /* Register debugfs interface */
 502        lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 503
 504        /* Install debugfs trigger files. */
 505        for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 506                struct crashpoint *cur = &crashpoints[i];
 507
 508                debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 509                                    &cur->fops);
 510        }
 511
 512        /* Install crashpoint if one was selected. */
 513        if (crashpoint) {
 514                ret = lkdtm_register_cpoint(crashpoint, crashtype);
 515                if (ret < 0) {
 516                        pr_info("Invalid crashpoint %s\n", crashpoint->name);
 517                        goto out_err;
 518                }
 519                pr_info("Crash point %s of type %s registered\n",
 520                        crashpoint->name, cpoint_type);
 521        } else {
 522                pr_info("No crash points registered, enable through debugfs\n");
 523        }
 524
 525        return 0;
 526
 527out_err:
 528        debugfs_remove_recursive(lkdtm_debugfs_root);
 529        return ret;
 530}
 531
 532static void __exit lkdtm_module_exit(void)
 533{
 534        debugfs_remove_recursive(lkdtm_debugfs_root);
 535
 536        /* Handle test-specific clean-up. */
 537        lkdtm_heap_exit();
 538        lkdtm_usercopy_exit();
 539
 540        if (lkdtm_kprobe != NULL)
 541                unregister_kprobe(lkdtm_kprobe);
 542
 543        pr_info("Crash point unregistered\n");
 544}
 545
 546module_init(lkdtm_module_init);
 547module_exit(lkdtm_module_exit);
 548
 549MODULE_LICENSE("GPL");
 550MODULE_DESCRIPTION("Kernel crash testing module");
 551